Police say they have "significant questions" for Mr Partington, who has officers waiting at his bedside for him to regain consciousness.

Sources say a domestic argument took place on the road in the hours before the blast.

Steve Heywood, Assistant Chief Constable of Greater Manchester Police, told a press conference in Shaw: "We have had some information to suggest it may not be accidental so we are treating it as a suspicious death and therefore a homicide investigation is undertaken."

Emergency crews have spent the day inspecting the damage

Mr Heywood added: "One of the early indications was that it may not have been an accident, therefore we will always then up the ante and treat it as a suspicious death inquiry.

"There might have been some precursor event, like a domestic incident. All those things are still in our thinking at this time."

Police said Mr Partington - a joiner originally from Rochdale - was still under sedation and unconscious at Wythenshawe Hospital, Manchester.

Officers will have to wait until doctors allow them to question him.

"He was a resident on the street at the time," Mr Heywood said, "and he is obviously somebody who we have significant questions for.

"His partner is currently being spoken to by specially trained officers in relation to what information she can give in relation to this investigation."

A child's toy house among the debris

Mr Heywood said it was only by chance that Michelle Heaton, the mother of the toddler who was killed, was not in the house when it was reduced to rubble in the explosion.

"The victim Jamie was in the house, we believe the front room, watching TV and his mother had just slipped out into the back yard, hanging out washing," he said.

"What that mother must be going through must be unbelievable, so our hearts go out to her."

During today's Prime Minister's Questions, he said: "I am sure the whole House will want to send a message of sympathy and condolences to the family of that poor two-year-old who lost their life, and also our best wishes to the burns victim who is in hospital being treated.

"The scenes were really quite appalling to see on our televisions and what had happened from that explosion."

Mr Cameron said he wanted pay tribute to the response of the emergency services "and also wish all speed to the police to get to the bottom of anything that might have happened here or anything that might have gone on".

"Everyone will require answers to what has been an absolute tragedy."

A refuge centre for people evacuated has been set up at a nearby school

Jamie Heaton's father, named locally as Kenny Heaton, was not at home at the time of the blast, around 11.15am on Tuesday.

The massive explosion flattened number 11 Buckley Street, where Jamie lived, and number 9, where Mr Partington lived.

The two houses are separated by an alleyway.

It is understood Mr Partington had only moved into the property around six weeks ago.

Surrounding properties were also devastated and structural engineers will have to check each house before residents can return.

Mr Heywood compared the scene to something like the IRA's bombing of Manchester.

"This looks like there has been a bomb. The devastation is absolutely tremendous. Our thoughts go out to those families that have been displaced."

Mr Heywood praised the way people and local businesses had come forward to help those hit by the disaster.

"The community support has been absolutely fantastic," he said.

Two houses on Buckley Street were completely destroyed

According to locals the property occupied by Mr Partington was rented from landlord and local businessman Iltaf Hussain.

Councillor Jean Stretton, from Oldham Council, said: "The response from the local community and partner groups to this tragic event has been heart-warming.

"In the immediate aftermath of the blast the local Asda supermarket gave up their restaurant to people evacuating the area, offering food and shelter and other items throughout the day.

"Several other local stores including Tesco and Primark also came forward with offers to assist in whatever way they could.

"A local taxi firm, Borough Taxis, took residents to the rest centre and we also have had so many offers of help from local residents.

"Even Crompton House pupils and staff assisted in setting up the facility this morning and also helped to ensure children were kept safe and well.

"In the face of such adversity everyone has pulled together in a fantastic community effort."